Method of making a quartz bar resonator

ABSTRACT

A suspension of a quartz bar including forming at least a pair of spaced forked electrodes interconnected by a blank in a single metallic sheet, folding the electrodes with respect to the blank, supporting at least a part of each of the electrodes from a base plate, removing the blank, and suspending a quartz bar upon said electrodes. Spacer legs adapted to be used to properly position the electrodes on the base may also be formed in the sheet and subsequently removed.

United States Patent 91 Engdahl Dec. 31, 1974 METHOD OF MAKING A QUARTZ BAR RESONATOR [75] Inventor: Jean Engdahl, Bienne, Switzerland [73] Assignee: Societe Suisse Pour LIndustrie Horlogere Management Services SA, Bienne Canton, Berne, Switzerland 22 Filed: Apr. 10, 1973 211 App]. No.: 349,674

[30] Foreign Application Priority Data Apr. 13, 1972 Switzerland 5472/72 [52] US. Cl 29/25.35, 29/628, 310/82, 310/91 [51-] Int. Cl B01j 17/00 [58] Field of Search 310/82, 9.1, 9.2, 9.3, 310/94, 8.9; 29/2542, 628

[56] References (Jited UNITED STATES PATENTS 2,155,035 4/1939 Bieling 310/94 X 2,409,838 lO/l946 Cress 310/94 2,434,903 l/l948 Bokovoy et a1... 3l0/9.4 2,457,145 12/1948 Gray 310/94 3,535,569 lO/1970 Clawson et al. 310/97 X 3,643,305 2/1972 Fumival 310/94 X 3,678,309 7/1972 Chotfat 310/94 X Primaty ExaminerCarl E. Hall Attorney, Agent, or Firm-Imirie, Smiley & Linn [5 7 ABSTRACT A suspension of a quartz bar including forming at least a pair of spaced forked electrodes interconnected by a blank in a single metallic sheet, folding the electrodes with respect to the blank, supporting at least a part of each of the electrodes from a base plate, removing the blank, and suspending a quartz bar upon said electrodes. Spacer legs adapted to be used to properly position the electrodes on the base may also be formed in the sheet and subsequently removed.

9 Claims, 6 Drawing Figures PATEHTED 1 1974 METHOD OF MAKING A QUARTZ BAR RESONATOR BACKGROUND OF THE INVENTION The present invention pertains to the suspension of a quartz bar between spaced pairs of electrodes, and more particularly, to a simply manufactured suspension assembly which assures precise spacing between such electrode pairs.

Suspensions of quartz are known where a bar of quartz is suspended in the region of the nodal points by means of metallic sheets, for example of bronze or cupro-beryllium. These metallic sheets or springs are placed approximately parallel to the longitudinal axis at the side of the quartz bar. Each sheet or spring is fixed separately to a supporting pin which passes through the bottom of the case or housing of the quartz bar. This suspension is relatively complicated and expensive and lacks the necessary rigidity to prevent variations of frequency of the quartz due to shocks.

SUMMARY OF THE INVENTION The present invention aims to remedy the aforementioned drawbacks with a particularly simple and effective suspension which avoids a deviation of frequency of the quartz due to a shock against the case or due to a permanent deformation of the suspending elements. The suspension of quartz according to the invention is characterized in that each pair of electrodes is made of one piece in the shape of a fork, one part thereof being embedded in the bottom of the quartz-case. This suspension not only has a high resistance to shocks, but also allows easy assembling without constraint.

In a preferred manufacturing process of the suspension according to the invention all electrodes are cut in one piece and folded into their mutual and definitive shape and position and parts of said electrode pairs are afterwards embedded in the bottom of the housing, the superfluous parts are removed to obtain separated electrode pairs, and the quartz is introduced between the electrodes and connected to them. This process allows the precise determination of the distance between the electrodes pairs, so that their fixation is simplified and assured exactly at the nodal points of the quartz bar.

The invention will be explained more in detail with reference to the drawings which show as a non limitative example two embodiments of the suspension according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1-3 show several steps in the fabrication of one embodiment of the suspension according to the present invention,

FIG. 4 shows a partial longitudinal cut of the finished quartz resonator with its case,

FIG. 5 is a transverse sectional view of the finished quartz with its case, and

FIG. 6 is a transverse sectional view of a second embodiment of the suspension.

DETAILED DESCRIPTION OF THE INVENTION For the realisation of the first embodiment of the suspension a cut metallic sheet as shown in FIG. 1 is used, where the cutting is made either by stamping or chemically. This metallic sheet has a central rectangular part 1 and legs 2 with predetermined length at each end. The sheet also contains generally Y-shaped, forked electrode pairs 3 at each end thereof. The sheet shown in FIG. 1 is then folded along the indicated dash-dotted lines to form the U-shaped piece shown in FIG. 2. It can be seen that the legs 2 and the electrode pairs 3 are in planes which are perpendicular to the plane of the median part 1. This piece is now put on the bottom 5 (FIG. 3) of the case in such a manner that the legs 2 rest practically without lateral play on a shoulder 6 of bottom 5. Thus, the position of the piece relative to bottom 5 is properly defined. A part of each electrode pair is then embedded in a glass bead 7, formed in an opening of bottom 5. The lower extremities of the electrode pairs form the terminals 8 of the quartz resonator assembly.

The median part 1 and the upper parts of the electrode pairs 3 and of the legs 2 are now cut along the dash-dotted lines shown in FIG. 3 and are removed so that separated pairs of electrodes 3 are obtained. Furthermore, by changing the length of the legs 2 it is possible to adjust the resonant frequency of the suspension and to optimalize the Q-factor of the resonator.

A bar of quartz 9 (FIG. 4) is then introduced from above between the electrode pairs and the electrodes are connected to a metallic coating which covers the lateral surfaces of the quartz bar by soft soldering. The distance between the two pairs of electrodes was exactly determined by the median part 1 when embedding the electrodes in the bead 7, and corresponds exactly to the distance between the nodal points of the quartz bar. Thus, a highly precise but nevertheless simplified device is obtained.

The FIGS. 4 and 5 show the terminated quartz in its case after the assembling of cover 10 and evacuation of the case.

The suspension of the quartz is particularly sturdy and prevents deviations of the frequency of the quartz due to shocks.

FIG. 6 shows a second embodiment differing from the above first embodiment in that the electrode pairs 3a have two terminals 8a and are generally H-shaped. Instead of a metallic bottom of the quartz-case and of embedding the electrode pairs in glass beads formed in holes of this metallic bottom, a bottom made of insulating material, such as for example glass or ceramics, may be used. These materials can be metallically coated at the spots where the connections pass and on the areas where the cover is fixed, whereas the electrode pairs and the cover can be fixed by soft soldering to the bottom.

What is claimed is:

1. A method of fabrication of a quartz bar resonator comprising the steps of forming at least a pair of spaced, forked electrodes interconnected by a blank in a single metallic sheet, folding said electrodes with respect to said blank, fixedly supporting at least a part of each of said electrodes from a base plate, removing said blank leaving said electrodes separately extending from said base plate, mounting a quartz bar at one end on one of said spaced electrodes and at the other end on another of said spaced electrodes, and connecting said quartz bar to said electrodes.

2. A method according to claim 1, wherein said pair of electrodes is formed at each end of said metallic sheet and said sheet is folded in a U-shaped configuration, whereby the forked electrode pairs are held together in fixed spaced relationship by the median blank of the folded sheet, and said median blank is removed after the fixed spaced relationship is maintained by supporting said electrodes from said base plate, and then the quartz bar is introduced between said forked electrodes so as to be supported in the region of its nodal points and connected thereto.

3. A method according to claim 1, wherein said electrodes are formed by mechanical cutting.

4. A method according to claim 1, wherein said electrodes are formed by chemical treatment.

5. A method according to claim 1, wherein said base plate is metallic, and wherein said electrode pairs are embedded in glass beads which are formed in openings of said base plate.

6. A method according to claim 5, wherein lateral legs are formed on the ends of said metallic sheet for 9. A method according to claim 1 further comprising positioning a cover over said quartz bar and connecting the same to said base plate. 

1. A method of fabrication of a quartz bar resonator comprising the steps of forming at least a pair of spaced, forked electrodes interconnected by a blank in a single metallic sheet, folding said electrodes with respect to said blank, fixedly supporting at least a part of each of said electrodes from a base plate, removing said blank leaving said electrodes separately extending from said base plate, mounting a quartz bar at one end on one of said spaced electrodes and at the other end on another of said spaced electrodes, and connecting said quartz bar to said electrodes.
 2. A method according to claim 1, wherein said pair of electrodes is formed at each end of said metallic sheet and said sheet is folded in a U-shaped configuration, whereby the forked electrode pairs are held together in fixed spaced relationship by the median blank of the folded sheet, and said median blank is removed after the fixed spaced relationship is maintained by supporting said electrodes from said base plate, and then the quartz bar is introduced between said forked electrodes so as to be supported in the region of its nodal points and connected thereto.
 3. A method according to claim 1, wherein said electrodes are foRmed by mechanical cutting.
 4. A method according to claim 1, wherein said electrodes are formed by chemical treatment.
 5. A method according to claim 1, wherein said base plate is metallic, and wherein said electrode pairs are embedded in glass beads which are formed in openings of said base plate.
 6. A method according to claim 5, wherein lateral legs are formed on the ends of said metallic sheet for resting on the base plate so as to determine the position of the electrodes and of the connected quartz bar relative to said base plate.
 7. A method according to claim 1, wherein said base plate is made of insulating material, and wherein said forked electrodes are supported by soft soldering in said base plate.
 8. A method according to claim 7, wherein said insulating material is either glass or ceramic and includes metallized areas to which said electrodes are soldered.
 9. A method according to claim 1 further comprising positioning a cover over said quartz bar and connecting the same to said base plate. 